Method of preserving soap and resulting product



pounds are used.

Patented 20, 1 945 METHOD OF PRESERVING SOAP AND RESULTING PRODUCT LloydF. Henderson, Reading, Mass., asslgnor to Lever Brothers Company, acorporation of Maine No. Drawing. Application February 6, 1943,

Serial N0. 475,001

14.01am. (Cl. zoo-398.5)

The present invention relates to detergent compositions derived fromhigher fatty materials and, more particularly, to soap and non-soapproducts comprising one or more ingredients which are Itis an advantageof this invention that the stabilizing substances which it i proposed toincorporate in the detergent do not have the property of impartingundesirable odor or of causing discoloration of the detergent as isfrequently the case when stabilizers, for example, phenolic compoundsare utilized for stabilizing purposes. Moreover, the group ofstabilizing substances used in accordance with the present invention arewater soluble and do not form precipitate as is sometimes the case whencertain metallic com- Furthermore, the present stabilizing substancesmay be utilized in comparatively small amounts based on the weight ofthe detergent whereby the amount of detergent in the product is notappreciably decreased, the physical characteristics of the detergent,for example, with respect to hardness, are not adversely affected, andthe cost of stabilizing the detergent is kept at a minimum.

By higher fatty detergent I refer to soaps and non-soaps having analiphatic radical of 8 or more carbon atoms. The soaps are the alkalimetal, ammonium, alkyl, amine and alkylolamine salts or esters of higherfatty acids such as may be prepared, for example, by saponifyinan animalor vegetable fat with an alkali metal compound. The higher fattynon-soap detergents are sulfonated or sulfated compounds such as higheralkyl sulfonates or sulfates, taurides, and other compounds derivedfromhigher fatty materials which group is well known in the art ashaving detergent properties. All compositions of this type, regardlessof the source of the ingredients or the technique of manufacture, may bestabilized in accordance with the present invention and all suchcompositions are intended to be within the scope of the invention. Forconvenience only. I

will describe my invention hereinafter as applied to soap. p 1

It is well known that soaps of the character described turn'ran cid as aresult of oxidation or otherwise. In the case of white soap there isusually a noticeable discoloration. It is an object of this invention toinhibit or retard this tendency to develop ra'ncidity without at thesame time incorporating large amounts of non-soap materials into thesoap and without causing undesirable collateral effects such as thedevelopment of undesirable color and odor, and softness.

The susceptibility to the development of rancidity which ischaracteristic of conventional soaps may be inhibited or retarded inaccordance with this invention by incorporating one or more of the groupof stabilizing substances herein disclosed, in the soap at anyconvenient stage of the soap making process. Preferably, the stabilizingsubstances are added to the soap subsequent to its boiling, for example,during crutching or milling, or both. The exact time at which thestabilizing substances are added or the method by which they are addedto the soap is not critical, and by the necessary to use onlyrelatlvelysmall amounts ofthe stabilizing substances inorder to effectaqebased on the weights of the soap and, in general,

less than 0.5% of stabilizer in the soap product is a desirable foradequate stabilization. There is no apparent advantage in utilizinggreater amounts of the stabilizer, and, therefore, it is preferred toutilize amounts within the above range, although amounts up to not morethan about 5% of stabllizer, based on the weight of the soap, may beemployed.

The group of stabilizing substances which may be used in accordance withthe invention are any of the aliphatic or aromatic compounds containingone or more trivalent nitrogens and two or more carboxyl groupsconnected to at least one of the nitrogens through a short aliphaticchain having not more than four carbon atoms and preferablythrough themethylene group. Such compounds would contain the essential group:

nooo-x HO O C-X where X is the above referred to short'aliphatic chain,such as CH2-. The following general formulas are illustrative of thetype of compounds above defined:

x--ooon x-ooon N x-ooon x-coon 7 in which x is a short aliphatic orsubstituted aliphatic chain; 7X is a hydrogen, alkyl, cycloalkyl, aryl,or substituted alkyl, cycloalkyl or aryl group, or a carboxyl alkylgroup containing not more than 4 carbon atoms in the chain portion ofthe molecule; Y is an aliphatic or substituted aliphatic chain, or anaromatic or cycloaliphatic nucleus. The carboxylates, including thesalts of the above acids, such as alkali metal, ammonium, and aminsalts, and the esters of the acids, such as the methyl and ethyl esters,as well as the anhydrides of the acids, are equally effective and areincluded within the above definition. When a carboxylate is used as thestabilizer the positive radical of the carboxylate preferably may betheisame as the positive radicalof the detergent. .Thus, an ammoniumsalt of one of the above acids would be used with an ammonium soap.

Among. the compositions of this type which may be used in accordancewith this invention are the alkali metal salts of, for example, thefollowing:

Nitrilotrlacetic acid Alkylene diamino tetracetic acidC-alkyl-nitriiotriacetic acid C-dialkyl nitrilotriacetic acidC-phenyl-nitriloiriacetic acid 'C-phenyI alkyl-nitrilotriacetic acidC-cyclohexenyl-nitrilotriacetic acid The above list of compounds isgiven merely by way of illustration and is not intended to be understoodas limitativeof the scope of the invention.

The nitrilodiacetic acid radical referred to in the specification andthe claims has the following formula:

CHzCOOH orncoon Nitrilotriacetic acid as the formula:

CHZCOOH N-crncoon cmooon soap. Samples of the resultingsoap andaddltional samples thereof prepared by adding small quantities of thestabilizing compounds during example, were carried out with asubstantially neutral kettle soap prepared by saponifying substantially'70 parts tallow and 25 parts coconut oil with 'suflicient caustic sodato make a neutral plodded and formed into cakes.

crutching were then permitted to stand at room conditions and also undercontrolled conditions of elevated temperature and high-humidity. At

theend of each day the soap was examined and any odor indicative ofrancidity was noted. The following table (Table I) of the resultsobtained with specific samples is given merely by way of illustrationand'is not to be understood as limiting the scope of the invention.

Table I D tic (test i d Stabilizing compound stabilizing V m n o r 0compound 115 F. R.%.

Per cent 7 N itrllotrlaoetic acid 0. 2 Rancid after 79 days. Ethigenediamlno tetracetic 0. 2 Good after 24! days.

ac Blank .1 None. Rancid after 3 days.

' tests directed to a milled type of soap. In carrying out theseadditional tests, soap chips of reduced moisture content were preparedin a conventional manner utilizing the-kettle soap stock referred toabove. Sampleamounts of the dried chips were then milled alone and witha small amount of a stabilizing compound added during the milling,following which the soap was The soap was then tested for stabilityagainst the development a of rancidity as describedabove. The followingtable (Table II) of the results obtained with specific samples which isgiven merely as illustrative, indicates that even superior results wereobtained in the case of a milled soap as compared with a framed type ofsoap.

- Table II Amotunt Duration of test period Stabilizing com- Magi? pounding comll5F. F. gg gi pound 80% R. H. 60% R. H. mm

Percem a Nitrllotriaoetic mi. 0.2 Rancid46 Good 202 Good 202 days. da s.days. Ethylene diamino 0. 2 Good 224 Goo 224 Good 224 tetracetic acid.days. days. days. Blank None Rancid 3 Rancid l3 Rancid ys d ysay In viewof the above data (TablesI and m, it

is apparent that stabilizing compoundsfselected from the group hereindisclosed possess marked stabilizing properties when incorporated insoap. Similar test results may be obtained by the use of compoundsselected from the group herein disclosed other than those whose testresults have been'specifically set forth in the tables above forillustrative purposes and the use of all such compounds in a soapcomposition'is intended to be within the scope of the presentinvention.'

least one of the nitrogens through a methylene I claim:

1. A detergent selected from the group consisting of soap and higherfatty non-soap detergents having a normal tendency to become rancid andbeing rendered resistant to the development of rancidity by havingincorporated therein a small amount of a non-detergent compound selectedgroup, and their salts, esters and anhydrides.

8. A method of retarding the development of ing at least onenitrilodiacetic acid radical.

from the group consisting of aliphatic and aromatic compounds containingat least one invalent nitrogen and at least two carboxyl groupsconnected to at least one of the nitrogens through a short aliphaticchain having not more than {our carbon atoms, and their salts, estersand anhydrides.

2. A detergent selected from the group consisting of soap and higherfatty non-soap detergents having a normal tendency to become rancid andbeing rendered resistant to the development of rancidity by havingincorporated therein a small amount of the order of about 0.01 to 1.0%,based on the weight of the detergent, of a non-detergent compoundselected from the group consisting of aliphatic and aromatic compoundscontaining at least one trivalent nitrogen and at least two carboxylgroups connected to at least one of the nitrogens through a methylenegroup, and their salts, esters and anhydrides.

3. A soap rendered resistant to the development of rancidity havingincorporated therein not more than 5% of an alkali metal salt of anorganic aminocarboxylic acid containing at least one nitrilodiaceticacid radical.

4. A soap rendered resistant to the development of rancidity havingincorporated therein a small amount of the order of about 0.01 to 1.0%of an alkali metal salt of nitrilotriacetic' acid.

, 5. A soap rendered resistant to the develop-.

ency to become rancid and being resistant to the ment of rancidityhaving incorporated thereima small'amount of the order of about 0.01 to1.0% 0! an alkali metal salt of ethylene diamino tetracetic acid. v

6. A- method of retarding the development of rancidity or a detergentselected from the group consisting of soap and higher fatty non-soapdetergents having a normal tendency. to become rancid, comprising.incorporating "in said detergent a small amount of a non-detergentcompound selected from the group consisting of aliphatic and aromaticcompounds containing at least one trivalent nitrogen and at leasttwo'carboxyl groups connected to at least one of the nitrogens through ashort aliphatic chain having not more than four carbon atoms, and theirsalts, estersand anhydrides,

'I. A method oi retardingthe development 'of rancidity of a detergentselected from, the group consisting of soap and higher fatty non-soapdetergents having a normal tendency to become rancid, comprisingincorporating insaid detera non-detergent compound selected from the.

group consisting of aliphatic and aromatic compounds containing at leastone trivalent nitrogen and at least two carboxyl groups connected to at-9 A method of retarding thedevelopment of rancidity of a soapcomprising incorporating in the-soap a small amount of the order'ofabout 0.01 to 1.0% of an alkali metal salt of nitrilotriacetic acid.

10. A method ofretarding the development of rancidity of a soapcomprising incorporating in the soap a small amount of the order ofabout 0.01 to 1.0%- of an alkali metal salt of ethylene diaminotetracetic acid. V i

11. An alkali metal soap having a normal tenddevelopment of rancidity byhaving incorporated therein not more than 5% of a non-detergent compoundselected from the group consisting of aliphatic and-aromatic compoundscontaining at least one trivalent nitrogen and at least two carboxylgroups connected to at least one of the the soap, of a non-detergentcompound selected from the group consisting of aliphatic andaromaticcompounds containing at least one tri- I valent nitrogen and at least,two carboxyl groups connected to at least one of the nitrogensthrough amethylene group, and their salts, esters and anhydrides. I

13. A method of retarding the development of rancidity in alkali metalsoaps having a-normal tendency to become rancid, which comprises 111-non-detergent compound selected from the group consisting of aliphaticand aromatic compounds containing at least one trivalent nitrogen and at1 least two carbonyl groups connected to at least 0 one of the nitrogensthrough a short aliphatic "chain having not more than four carbon'atoms,and their salts, esters and anhydrides.

14. A method of retarding the development of rancidity in alkali metalsoaps having a normal tendency to become rancid, which comprisesincorporating in the soap a small amountof the order of about 0.01% to1.0%, based on the tveight of the soap, oi anon-detergent compoundselected from the group consisting of aliphatic and aromatic compoundscontaining at least one tri- Q, valent nitrogen and at least twocarbonyl groups connected to at least one oi. the nitrogens through amethylene group, and their salts, esters and anhydrides. r

LLOYD F. HENDERSON.

corporating in the soap not more than 5% of a Patent no. 2, 71,62

CERTIFICATE OF CORRECTION.

. r 20, 1.915- LLOYD F. HENDERSON.

It is hereby certified that error appears in the printed specification 7of the above numbered patent requiring correction as follows: Page 1,first column, line 7, for "the" read -this--; page 2, first coluinn,line .57,

for "acid as" read --acid hasline Tip, for "'70 parts" read -75 parts--;

and second column, line 20, Table 1, third colnnin 55601"; for theindistinct numeral before "days read --2L|.7 and that the said LettersPatent should be read with this correction therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 5th dayof June, A. D5 1915.

Leslie Frazer (Seal). Acting Commissioner of Patents.

